In response to ongoing controversy over views such as that African countries suffer chronic poverty and illness because their people have lower IQs and that black women are objectively less attractive than women of other races, he was dismissed from writing for Psychology Today. His employer – the London School of Economics – prohibited him from publishing in non-peer-reviewed outlets for 12 months,[6] and a group of 68 evolutionary psychologists issued an open letter titled "Kanazawa's bad science does not represent evolutionary psychology",[7] and an article was published by 35 on the same theme.[8]

In February 2008, he started a blog on Psychology Today called "The Scientific Fundamentalist." He was dismissed after the controversy over his "Why Are Black Women Less Physically Attractive Than Other Women?" article in May 2011.

In September 2012, after the period of 12 months when he was prohibited from publishing in non-peer-reviewed outlets by the LSE, he was hired by the blog Big Think as a contributing editor; the co-operation was discontinued on 29 March 2013.[10]

Why Beautiful People Have More Daughters: From Dating, Shopping, and Praying to Going to War and Becoming a Billionaire—Two Evolutionary Psychologists Explain Why We Do What We Do

Why Men Gamble and Women Buy Shoes: How Evolution Shaped the Way We Behave

Order by Accident: The Origins and Consequences of Conformity in Contemporary Japan

He also wrote a blog, The Scientific Fundamentalist, for Psychology Today until his dismissal in 2011.[11]

Kanazawa uses the term Savanna principle to denote the theory that societal difficulties exist because "the human brain" evolved in Africa hundreds of thousands of years ago, a drastically different environment from today's urban, industrial society.[12] In 2003, in an article in the Journal of Research in Personality, he claimed to show that scientists generally made their biggest discoveries before their mid-30s, and compared this productivity curve to that of criminals.[13]

In 2006, he published an article in the Journal of Theoretical Biology, claiming that attractive people are 26% less likely to have male offspring.[14][15] In a letter to the editors regarding Kanazawa's claim that attractive people are more likely to have daughters,[16]Columbia statistician Andrew Gelman points out that a correct interpretation of the regression coefficients in Kanazawa's analysis is that attractive people are 8% more likely to have girls, an error that Kanazawa acknowledges.[17] Gelman argues that Kanazawa's analysis does not convincingly show causality, because of possible endogeneity as well as problematic interpretations of statistical significance in multiple comparisons. While Kanazawa claims that the former error is "merely linguistic" and that he addressed the latter two in his initial article,[15] Gelman maintains that his original criticism remains valid.[18]

In May 2011, he published an article in Psychology Today that explored why black women had been rated less attractive than those of other races in the National Longitudinal Study of Adolescent Health. Subsequent critical independent analysis of the results showed that the difference in assessed attractiveness held for three of the four data sets in the National Longitudinal Study of Adolescent Health and that there was only a statistically significant race difference in younger women and that it disappeared by early adulthood.[19] Applying his same reasoning to males, Kanazawa also concluded in his article that black men would generally be considered more attractive. Kanazawa was also criticised for arguing that the common factor of subjective interviewer ratings of attractiveness used in his analysis constitutes an objective scale of attractiveness.[20]

The article caused outrage and was widely criticised. The first criticisms were published in the blogosphere leading to the creation of petitions on Change.org and Facebook to have Kanazawa fired.[21] But also other scientists, including a group of evolutionary psychologists publishing a joint statement published criticisms, distancing the discipline of evolutionary psychology from Kanazawa's research.[7]Psychology Today pulled the article and on 27 May 2011, issued an apology to anyone who had been offended and stated that they had not reviewed Kanazawa's article before its publication,[22] and stated that they would police more strictly for controversial content in the future.[11]

In September 2011, Kanazawa apologised to LSE director Judith Rees, saying he "deeply regrets" the "unintended consequences" of the blog and accepting that "some of [his] arguments may have been flawed and not supported by the available evidence." An internal LSE investigation found that Kanazawa had brought the school into disrepute and prohibited him from publishing in non-peer-reviewed outlets for a year.[23] Following the controversy, an open letter was signed by 68 evolutionary psychologists distancing themselves from Kanazawa and defending evolutionary psychology, writing "The principle of applying evolutionary theory to the study of human psychology and behaviour is sound, and there is a great deal of high-quality, nuanced, culturally-sensitive evolutionary research ongoing in the UK and elsewhere today."[7] In response, an international group of 23 scientists published a letter in Times Higher Education defending Kanazawa's work.[24]

In a 2008 blog post for Psychology Today titled "Why we are losing this war", Kanazawa claims that Americans are unable to win in the Middle East—and in the "global clash of civilizations"—because they do not hate their enemies enough.[25] His blog post continued: "Imagine that, on September 11, 2001, when the Twin Towers came down, the President of the United States was not George W. Bush, but Ann Coulter. What would have happened then? On September 12, President Coulter would have ordered the US military forces to drop 35 nuclear bombs throughout the Middle East, killing all of our actual and potential enemy combatants, and their wives and children. On September 13, the war would have been over and won, without a single American life lost."

In 2006, Kanazawa used the "Savanna principle" to explain the correlation of health and IQ vs. health and wealth. He argued that IQ is a better predictor for health than wealth or inequality in most regions of the world, except in Sub-Saharan Africa, where health is more strongly correlated to wealth than to IQ, because Sub-Saharan Africa represents an "evolutionary familiar" environment with lesser selection pressure on IQ than elsewhere.[26] In a criticism of the paper George Ellison (2007) argued that the conclusion was based on "flawed assumptions, questionable data, inappropriate analysis and biased interpretations".[27]

In 2012, Kanazawa wrote that a "'multicultural society' is a logical and physical impossibility." He said that "the artificial language of Esperanto never took off, despite its numerous favorable linguistic features" because "language cannot exist without a society of speakers speaking it daily and interacting with each other."[28]